Methods of and apparatus for making high aspect ratio microelectromechanical structures

ABSTRACT

Various embodiments of the invention provide techniques for forming structures (e.g. HARMS-type structures) via an electrochemical extrusion process. Preferred embodiments perform the extrusion processes via depositions through anodeless conformable contact masks that are initially pressed against substrates that are then progressively pulled away or separated as the depositions thicken. A pattern of deposition may vary over the course of deposition by including more complex relative motion between the mask and the substrate elements. Such complex motion may include rotational components or translational motions having components that are not parallel to an axis of separation. More complex structures may be formed by combining the electrochemical extrusion process with the selective deposition, blanket deposition, planarization, etching, and multi-layer operations of a multi-layer electrochemical fabrication process.

RELATED CASES

This application claims priority to U.S. Provisional Patent ApplicationNo. 60/329,654 which was filed on Oct. 15, 2001 and which isincorporated herein by reference as if set forth in full.

FIELD OF THE INVENTION

The present invention relates generally to the field of ElectrochemicalFabrication and the associated formation of three-dimensional structures(e.g. micro-scale or meso-scale structures). In particular, it relatesto methods and apparatus for forming such three-dimensional structuresusing electrochemical deposition techniques, and even more particularlyrelates to the electrochemical extrusion of such structures via therelative movement of a mask and a substrate.

BACKGROUND OF THE INVENTION

A technique for forming three-dimensional structures (e.g. parts,components, devices, and the like) from a plurality of adhered layerswas invented by Adam L. Cohen and is known as ElectrochemicalFabrication. It is being commercially pursued by Microfabrica Inc. ofBurbank, Calif. under the tradename EFAB™. This technique was describedin U.S. Pat. No. 6,027,630, issued on Feb. 22, 2000. Thiselectrochemical deposition technique allows the selective deposition ofa material using a unique masking technique that involves the use of amask that includes patterned conformable material on a support structurethat is independent of the substrate onto which plating will occur. Whendesiring to perform an electrodeposition using the mask, the conformableportion of the mask is brought into contact with a substrate while inthe presence of a plating solution such that the contact of theconformable portion of the mask to the substrate inhibits deposition atselected locations. For convenience, these masks might be genericallycalled conformable contact masks; the masking technique may begenerically called a conformable contact mask plating process. Morespecifically, in the terminology of Microfabrica Inc. such masks havecome to be known as INSTANT MASKS™ and the process known as INSTANTMASKING™ or INSTANT MASK™ plating. Selective depositions usingconformable contact mask plating may be used to form single layers ofmaterial or may be used to form multi-layer structures. The teachings ofthe '630 patent are hereby incorporated herein by reference as if setforth in full herein. Since the filing of the patent application thatled to the above noted patent, various papers about conformable contactmask plating (i.e. INSTANT MASKING) and electrochemical fabrication havebeen published:

-   -   1. A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.        Will, “EFAB: Batch production of functional, fully-dense metal        parts with micro-scale features”, Proc. 9th Solid Freeform        Fabrication, The University of Texas at Austin, p161, Aug. 1998.    -   2. A. Cohen, G. Zhang, F. Tseng, F. Mansfeld, U. Frodis and P.        Will, “EFAB: Rapid, Low-Cost Desktop Micromachining of High        Aspect Ratio True 3-D MEMS”, Proc. 12th IEEE Micro Electro        Mechanical Systems Workshop, IEEE, p244, January 1999.    -   3. A. Cohen, “3-D Micromachining by Electrochemical        Fabrication”, Micromachine Devices, March 1999.    -   4. G. Zhang, A. Cohen, U. Frodis, F. Tseng, F. Mansfeld, and P.        Will, “EFAB: Rapid Desktop Manufacturing of True 3-D        Microstructures”, Proc. 2nd International Conference on        Integrated MicroNanotechnology for Space Applications, The        Aerospace Co., Apr. 1999.    -   5. F. Tseng, U. Frodis, G. Zhang, A. Cohen, F. Mansfeld, and P.        Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal        Microstructures using a Low-Cost Automated Batch Process”, 3rd        International Workshop on High Aspect Ratio MicroStructure        Technology (HARMST '99), June 1999.    -   6. A. Cohen, U. Frodis, F. Tseng, G. Zhang, F. Mansfeld, and P.        Will, “EFAB: Low-Cost, Automated Electrochemical Batch        Fabrication of Arbitrary 3-D Microstructures”, Micromachining        and Microfabrication Process Technology, SPIE 1999 Symposium on        Micromachining and Microfabrication, September 1999.    -   7. F. Tseng, G. Zhang, U. Frodis, A. Cohen, F. Mansfeld, and P.        Will, “EFAB: High Aspect Ratio, Arbitrary 3-D Metal        Microstructures using a Low-Cost Automated Batch Process”, MEMS        Symposium, ASME 1999 International Mechanical Engineering        Congress and Exposition, November, 1999.    -   8. A. Cohen, “Electrochemical Fabrication (EFABTM)”, Chapter 19        of The MEMS Handbook, edited by Mohamed Gad-El-Hak, CRC Press,        2002.    -   9. “Microfabrication—Rapid Prototyping's Killer Application”,        pages 1–5 of the Rapid Prototyping Report, CAD/CAM Publishing,        Inc., June 1999.

The disclosures of these nine publications are hereby incorporatedherein by reference as if set forth in full herein.

The electrochemical deposition process may be carried out in a number ofdifferent ways as set forth in the above patent and publications. In oneform, this process involves the execution of three separate operationsduring the formation of each layer of the structure that is to beformed:

-   -   1. Selectively depositing at least one material by        electrodeposition upon one or more desired regions of a        substrate.    -   2. Then, blanket depositing at least one additional material by        electrodeposition so that the additional deposit covers both the        regions that were previously selectively deposited onto, and the        regions of the substrate that did not receive any previously        applied selective depositions.    -   3. Finally, planarizing the materials deposited during the first        and second operations to produce a smoothed surface of a first        layer of desired thickness having at least one region containing        the at least one material and at least one region containing at        least the one additional material.

After formation of the first layer, one or more additional layers may beformed adjacent to the immediately preceding layer and adhered to thesmoothed surface of that preceding layer. These additional layers areformed by repeating the first through third operations one or more timeswherein the formation of each subsequent layer treats the previouslyformed layers and the initial substrate as a new and thickeningsubstrate.

Once the formation of all layers has been completed, at least a portionof at least one of the materials deposited is generally removed by anetching process to expose or release the three-dimensional structurethat was intended to be formed.

The preferred method of performing the selective electrodepositioninvolved in the first operation is by conformable contact mask plating.In this type of plating, one or more conformable contact (CC) masks arefirst formed. The CC masks include a support structure onto which apatterned conformable dielectric material is adhered or formed. Theconformable material for each mask is shaped in accordance with aparticular cross-section of material to be plated. At least one CC maskis needed for each unique cross-sectional pattern that is to be plated.

The support for a CC mask is typically a plate-like structure formed ofa metal that is to be selectively electroplated and from which materialto be plated will be dissolved. In this typical approach, the supportwill act as an anode in an electroplating process. In an alternativeapproach, the support may instead be a porous or otherwise perforatedmaterial through which deposition material will pass during anelectroplating operation on its way from a distal anode to a depositionsurface. In either approach, it is possible for CC masks to share acommon support, i.e. the patterns of conformable dielectric material forplating multiple layers of material may be located in different areas ofa single support structure. When a single support structure containsmultiple plating patterns, the entire structure is referred to as the CCmask while the individual plating masks may be referred to as“submasks”. In the present application such a distinction will be madeonly when relevant to a specific point being made.

In preparation for performing the selective deposition of the firstoperation, the conformable portion of the CC mask is placed inregistration with and pressed against a selected portion of thesubstrate (or onto a previously formed layer or onto a previouslydeposited portion of a layer) on which deposition is to occur. Thepressing together of the CC mask and substrate occur in such a way thatall openings, in the conformable portions of the CC mask contain platingsolution. The conformable material of the CC mask that contacts thesubstrate acts as a barrier to electrodeposition while the openings inthe CC mask that are filled with electroplating solution act as pathwaysfor transferring material from an anode (e.g. the CC mask support) tothe non-contacted portions of the substrate (which act as a cathodeduring the plating operation) when an appropriate potential and/orcurrent are supplied.

An example of a CC mask and CC mask plating are shown in FIGS. 1A–1C.FIG. 1A shows a side view of a CC mask 8 consisting of a conformable ordeformable (e.g. elastomeric) insulator 10 patterned on an anode 12. Theanode has two functions. One is as a supporting material for thepatterned insulator 10 to maintain its integrity and alignment since thepattern may be topologically complex (e.g., involving isolated “islands”of insulator material). The other function is as an anode for theelectroplating operation. FIG. 1A also depicts a substrate 6 separatedfrom mask 8. CC mask plating selectively deposits material 22 onto asubstrate 6 by simply pressing the insulator against the substrate thenelectrodepositing material through apertures 26 a and 26 b in theinsulator as shown in FIG. 1B. After deposition, the CC mask isseparated, preferably non-destructively, from the substrate 6 as shownin FIG. 1C. The CC mask plating process is distinct from a“through-mask” plating process in that in a through-mask plating processthe separation of the masking material from the substrate would occurdestructively. As with through-mask plating, CC mask plating depositsmaterial selectively and simultaneously over the entire layer. Theplated region may consist of one or more isolated plating regions wherethese isolated plating regions may belong to a single structure that isbeing formed or may belong to multiple structures that are being formedsimultaneously. In CC mask plating, as individual masks are notintentionally destroyed in the removal process, they may be usable inmultiple plating operations.

Another example of a CC mask and CC mask plating is shown in FIGS.1D–1G. FIG. 1D shows an anode 12′ separated from a mask 8′ thatcomprises a patterned conformable material 10′ and a support structure20. FIG. 1D also depicts substrate 6 separated from the mask 8′. FIG. 1Eillustrates the mask 8′ being brought into contact with the substrate 6.FIG. 1F illustrates the deposit 22′ that results from conducting acurrent from the anode 12′ to the substrate 6. FIG. 1G illustrates thedeposit 22′ on substrate 6 after separation from mask 8′. In thisexample, an appropriate electrolyte is located between the substrate 6and the anode 12′ and a current of ions coming from one or both of thesolution and the anode are conducted through the opening in the mask tothe substrate where material is deposited. This type of mask may bereferred to as an anodeless INSTANT MASK™ (AIM) or as an anodelessconformable contact (ACC) mask.

Unlike through-mask plating, CC mask plating allows CC masks to beformed completely separate from the fabrication of the substrate onwhich plating is to occur (e.g. separate from a three-dimensional (3D)structure that is being formed). CC masks may be formed in a variety ofways, for example, a photolithographic process may be used. All maskscan be generated simultaneously prior to structure fabrication ratherthan during it. This separation makes possible a simple, low-cost,automated, self-contained, and internally-clean “desktop factory” thatcan be installed almost anywhere to fabricate 3D structures, leaving anyrequired clean room processes, such as photolithography to be performedby service bureaus or the like.

An example of the electrochemical fabrication process discussed above isillustrated in FIGS. 2A–2F. These figures show that the process involvesdeposition of a first material 2 which is a sacrificial material and asecond material 4 which is a structural material. The CC mask 8, in thisexample, includes a patterned conformable material (e.g. an elastomericdielectric material) 10 and a support 12 which is made from depositionmaterial 2. The conformal portion of the CC mask is pressed againstsubstrate 6 with a plating solution 14 located within the openings 16 inthe conformable material 10. An electric current, from power supply 18,is then passed through the plating solution 14 via (a) support 12 whichdoubles as an anode and (b) substrate 6 which doubles as a cathode. FIG.2A, illustrates that the passing of current causes material 2 within theplating solution and material 2 from the anode 12 to be selectivelytransferred to and plated on the substrate 6. After electroplating thefirst deposition material 2 onto the substrate 6 using CC mask 8, the CCmask 8 is removed as shown in FIG. 2B. FIG. 2C depicts the seconddeposition material 4 as having been blanket-deposited (i.e.non-selectively deposited) over the previously deposited firstdeposition material 2 as well as over the other portions of thesubstrate 6. The blanket deposition occurs by electroplating from ananode (not shown), composed of the second material, through anappropriate plating solution (not shown), and to the cathode/substrate6. The entire two-material layer is then planarized to achieve precisethickness and flatness as shown in FIG. 2D. After repetition of thisprocess for all layers, the multi-layer structure 20 formed of thesecond material 4 (i.e. structural material) is embedded in firstmaterial 2 (i.e. sacrificial material) as shown in FIG. 2E. The embeddedstructure is etched to yield the desired device, i.e. structure 20, asshown in FIG. 2F.

Various components of an exemplary manual electrochemical fabricationsystem 32 are shown in FIGS. 3A–3C. The system 32 consists of severalsubsystems 34, 36, 38, and 40. The substrate holding subsystem 34 isdepicted in the upper portions of each of FIGS. 3A to 3C and includesseveral components: (1) a carrier 48, (2) a metal substrate 6 onto whichthe layers are deposited, and (3) a linear slide 42 capable of movingthe substrate 6 up and down relative to the carrier 48 in response todrive force from actuator 44. Subsystem 34 also includes an indicator 46for measuring differences in vertical position of the substrate whichmay be used in setting or determining layer thicknesses and/ordeposition thicknesses. The subsystem 34 further includes feet 68 forcarrier 48 which can be precisely mounted on subsystem 36.

The CC mask subsystem 36 shown in the lower portion of FIG. 3A includesseveral components: (1) a CC mask 8 that is actually made up of a numberof CC masks (i.e. submasks) that share a common support/anode 12, (2)precision X-stage 54, (3) precision Y-stage 56, (4) frame 72 on whichthe feet 68 of subsystem 34 can mount, and (5) a tank 58 for containingthe electrolyte 16. Subsystems 34 and 36 also include appropriateelectrical connections (not shown) for connecting to an appropriatepower source for driving the CC masking process.

The blanket deposition subsystem 38 is shown in the lower portion ofFIG. 3B and includes several components: (1) an anode 62, (2) anelectrolyte tank 64 for holding plating solution 66, and (3) frame 74 onwhich the feet 68 of subsystem 34 may sit. Subsystem 38 also includesappropriate electrical connections (not shown) for connecting the anodeto an appropriate power supply (not shown) for driving the blanketdeposition process.

The planarization subsystem 40 is shown in the lower portion of FIG. 3Cand includes a lapping plate 52 and associated motion and controlsystems (not shown) for planarizing the depositions.

In the last decade or so, there has been interest in creating MEMSdevices whose overall height is comparable to or greater than theirlateral extents; such structures are called high aspect ratiomicrostructures, or “HARMS”. Two processes have emerged to dominate themanufacture of HARMS. They are LIGA and deep reactive ion etching(DRIE). LIGA is used to form metal structures and via secondary moldingoperations it may be used to produce polymer and ceramics structures.DRIE is used for etching deep holes into silicon.

The LIGA process is illustrated in FIGS. 4A–4G. The process isessentially based on “through-mask plating” using a very thick patternedresist (e.g., 100s of microns to a centimeter or more). The resist ispatterned using extremely high energy X-rays (e.g., >1 GeV) which allowsthe radiation to penetrate through the thick resist without significantattenuation or scattering. This, combined with a highly-collimatedsynchrotron beam, makes possible the fabrication of structures with verystraight and parallel sidewalls having very smooth surfaces.

In FIG. 4A a substrate 81 is prepared (e.g., by planarizing, cleaning,and depositing a conductive plating base (not shown). In FIG. 4B a thicklayer of polymer 82 serving as an X-ray resist (typicallypoly(methylmethacrylate), or PMMA), is bonded to the plating base. Asshown in FIG. 4C the resist 82 is exposed to energetic X-rays 83 througha specially-fabricated patterned mask 84 that may for example includegold patterning 85 on a silicon or graphite base 86. The exposurerenders certain areas of the resist soluble in a developing chemical.FIG. 4D shows the patterned resist after development yielding mask 87,which has openings that extend to the plating base on the substrate 81.Next a through-mask selective electroplating operation occurs. FIG. 4Eshows the substrate 81 with mask 87 immersed in a deposition bath 88held in a deposition tank 89, an anode 91; electrical connections 92 and93 connecting the anode and substrate to a power supply 94. When currentis applied, a metal 99' (or other electrodepositable material) isdeposited onto the exposed plating base of substrate 81. If a low-stressformulation and deposition parameters are employed, the deposition canbe continued to yield a thick deposit of metal (or other material) 99 asshown in FIG. 4F. Then, as is shown in FIG. 4G, the mask 87 can beremoved (usually chemically) to yield the released deposited structure100 comprising metal 99. If desired, this microstructure 100 can then beused for molding other materials such as polymers or ceramics, forexample, using injection molding or embossing techniques, for massproduction.

Materials typically electrodeposited in LIGA are pure metals such as Ni,Cu, and Au, or metal alloys such as Ni—Fe (e.g., Permalloy). The latteris challenging due to limited mass transfer in the high aspect ratiomask. Also composite materials such as Ni and SiC can be deposited.

Because of the high cost of LIGA and an associated shortage ofinfrastructure, efforts have been made recently to develop alternativemethods of fabricating through-mask electrodeposition masks withreasonably high aspect ratios (though much lower than those attainablewith LIGA). One such effort is “UV-LIGA”, in which a UV-curable resistis used (e.g., a negative-working photoresist called SU-8, which is anepoxy based photopolymer, has been available commercially for severalyears). Though SU-8 can achieve reasonably vertical sidewalls andthicknesses up to several hundred microns, it is extremely difficult toremove after the electrodeposition process is completed.

Another method that has been explored is sometimes known as Laser LIGA:it involves the use of a laser (typically a UV excimer laser) to machinecavities in a polymer to form a mask. This technique can create masks upto several tens of microns thick, but the sidewalls tend to be tapered(i.e., not parallel) and somewhat rough.

A need exists for a more cost effective HARMS technology. A need existsfor a HARMS technology that is compatible with the formation of HARMSdevices on substrates containing microelectronic devices (e.g., a CMOSwafer). A need exists for a HARMS technology that results in structureshaving more uniform properties throughout their heights. This isparticularly true when deposition of alloying materials is to occur(inhibition of ionic transport into deep through-masks can vary by ionicspecifies and by depth level in the mask). A need exists for a HARMStechnology that allows formation of more complex structures.

SUMMARY OF THE INVENTION

It is an object of various aspects of the present invention, or ofvariations thereof, to provide a more cost effective HARMS-typetechnology.

It is an object of various aspects of the present invention, or ofvariations thereof, to provide a HARMS-type technology that iscompatible with the formation of HARMS devices on substrates containingmicroelectronic devices.

It is an object of various aspects of the present invention, or ofvariations thereof, to provide a HARMS-type technology that results instructures having more uniform properties throughout their heights.

It is an object of various aspects of the present invention, or ofvariations thereof, to provide a HARMS-type technology that allowsformation of more complex structures.

It is an object of various aspects of the present invention, or ofvariations thereof, to provide enhanced electrochemical fabricationtechniques that can be used to supplement the formation capabilitiesassociated with CC mask plating.

It is an object of various aspects of the present invention, or ofvariations thereof, to provide enhanced electrochemical formationcapabilities

It is an object of various aspects of the present invention, or ofvariations thereof, to expand the range of materials that can be used inHARMS-type applications.

Other objects and advantages of various aspects of the invention will beapparent to those of skill in the art upon review of the teachingsherein. The various aspects of the invention, set forth explicitlyherein or otherwise ascertained from the teaching herein, may addressany one of the above objects alone or in combination, or alternativelymay address some other object of the invention ascertained from theteachings herein. It is not intended that all of these objects beaddressed by any single aspect of the invention even though that may bethe case with regard to some aspects.

In a first aspect of the invention, a method of producing athree-dimensional structure includes providing an anode; providing asubstrate that functions as a cathode; providing an electrolyte betweenthe anode and the cathode; providing a current source controllablyconnected to the anode and cathode; providing a dielectric mask thatincludes an at least partially conformable material, the mask having atleast one opening extending through the conformable material wherein theopening is defined by mask sidewalls and wherein the opening defines amask pattern, the conformable portion of the mask also having a facesurface; pressing the face surface of the mask against the substrate;after pressing, activating the current source to cause deposition of adeposition material onto the substrate in a deposition pattern at leastpartially dictated by the pattern of the mask, wherein the depositionincludes deposition sidewalls; and after said activating, relativelymoving the face surface of the mask away from the substrate by adistance that is less than a distance that would cause separation of themask sidewalls from the deposition sidewalls, and continuing applicationof the current so as to allow a height of the deposition to increase.

In a second aspect of the invention, a method of producing athree-dimensional structure includes providing a substrate on whichdeposition of a material can occur; providing a mask having a patternthat includes a masking material and at least one opening therein,wherein the masking material surrounding the opening forms masksidewalls; selectively depositing material onto the substrate while themask is mated thereto either via a face of the mask or the masksidewalls and thereafter relatively separating the mask from thesubstrate while maintaining contact between the mask sidewalls and thedeposited material and continuing the deposition of material so that aheight of deposition increases beyond what it was prior to beginning theseparation of the mask and the substrate.

In a third aspect of the invention, an apparatus for producing athree-dimensional structure includes an electrode that can beelectrically biased to function as an erodable anode; a substrate onwhich a deposition material may be deposited and which can beelectrically biased as a cathode; a container for holding an electrolytethat can form a conductive path between the electrode and the substrate;a current source controllably connected to the electrode and thesubstrate; a dielectric mask that that includes an at least partiallyconformable material, the mask having at least one opening extendingthrough the conformable material wherein the opening is defined by masksidewalls and wherein the opening defines a mask pattern, theconformable portion of the mask also having a face surface; means formating the face surface of the mask against the substrate; means foractivating the current source to cause deposition of a depositionmaterial onto the substrate in a deposition pattern at least partiallydictated by the pattern of the mask, wherein the deposition includesdeposition sidewalls; and means for relatively moving the face surfaceof the mask away from the substrate by a distance that is less than adistance that would cause separation of the mask sidewalls from thedeposition sidewalls, and continuing application of the current so as toallow a height of the deposition to increase.

In a fourth aspect of the invention, an apparatus for producing athree-dimensional structure includes an electrode that can beelectrically biased to function as an erodable anode; a substrate onwhich a deposition material may be deposited and which can beelectrically biased as a cathode; a container for holding an electrolytethat can form a conductive path between the electrode and the substrate;a current source controllably connected to the electrode and thesubstrate; a dielectric mask that includes an at least partiallyconformable material, the mask having at least one opening extendingthrough the conformable material wherein the opening is defined by masksidewalls and wherein the opening defines a mask pattern, theconformable portion of the mask also having a face surface; at least onecontrollable stage for positioning the face surface of the mask againstthe substrate and for moving the face surface of the mask away from thesubstrate by a distance that is less than a distance that would causeseparation of the mask sidewalls from the deposition sidewalls; acontroller for (1) activating the current source to cause deposition ofa deposition material onto the substrate in a deposition pattern atleast partially dictated by the pattern of the mask, wherein thedeposition includes deposition sidewalls; (2) causing the substrate andthe face surface of the mask to contact and then, after a desired amountof deposition, to separate the deposit from the face surface of themask; and (3) continuing application of the current after incrementalpulling away, during continuous relative pulling away of the substratefrom the mask, or during movement that causes separation so as to allowa height of the deposition to increase.

In a fifth aspect of the invention, a method of producing athree-dimensional structure, includes: providing a substrate from whicha pattern protrudes, where the pattern has pattern sidewalls and thesubstrate has a face surface that is approximately perpendicular to thesidewalls; providing a mask, having a pattern, that includes a maskingmaterial and at least one opening therein, wherein the masking materialhas a face surface that is substantially parallel to the face of thesubstrate and wherein the masking material, surrounding the openingforms mask sidewalls; and mating the mask sidewalls with the patternsidewalls without mating the face surface of the masking material withthe face surface of the substrate and depositing material through theopening onto the substrate.

In a sixth aspect of the invention a method of producing athree-dimensional structure, includes: providing an anode; providing asubstrate that functions as a cathode, where the substrate includes aface surface and may include a protrusion having sidewalls that extendsfrom the face surface; providing an electrolyte between the anode andthe cathode; providing a current source controllably connected to theanode and cathode; providing a dielectric mask that includes an at leastpartially conformable material, the mask having at least one openingextending through the conformable material wherein the opening isdefined by mask sidewalls and wherein the opening defines a maskpattern, the conformable portion of the mask also having a face surface;mating the face surface of the mask against the face surface of thesubstrate, or mating the mask sidewalls to the sidewalls of theprotrusion; after mating, activating the current source to causedeposition of a deposition material onto the substrate in a depositionpattern that is at least partially dictated by the pattern of the mask,wherein the deposition includes deposition sidewalls; and after saidactivating, relatively moving the face surface of the mask away from thesubstrate by a distance that is less than a distance that would causeseparation of the mask sidewalls from at least one of the protrusionsidewalls or the deposition sidewalls, and continuing application of thecurrent so as to allow a height of the deposition to increase.

Further aspects of the invention will be understood by those of skill inthe art upon reviewing the teachings herein. Other aspects of theinvention may involve combinations of the above noted aspects of theinvention. Other aspects of the invention may involve apparatus that canbe used in implementing one or more of the above method aspects of theinvention. These other aspects of the invention may provide variouscombinations of the aspects presented above as well as provide otherconfigurations, structures, functional relationships, and processes thathave not been specifically set forth above.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A–1C schematically depict a side view of various stages of a CCmask plating process, while FIGS. 1D–1G depict a side view of variousstages of CC mask plating process using a different type of CC mask.

FIGS. 2A–2F schematically depict side views of various stages of anelectrochemical fabrication process as applied to the formation of aparticular structure where a sacrificial material is selectivelydeposited while a structural material is blanket deposited.

FIGS. 3A–3C schematically depict side views of various examplesubassemblies that may be used in manually implementing theelectrochemical fabrication method depicted in FIGS. 2A–2F.

FIGS. 4A–4G depict side views of various stages in a LIGA process forforming a HARMS-type structure.

FIGS. 5A–5F depict side views of various stages in a process accordingto a preferred embodiment of the present invention.

FIG. 6 depicts a side view of a structure formed according to apreferred embodiment where the motion between the mask and the substrateincluded both perpendicular movement and parallel movement such that adesired amount of lateral variation in the deposit occurred.

FIGS. 7A–7C depict side views of various stages in a process accordingto a preferred embodiment of the present invention while FIG. 7D depictsan alternate configuration for sealing the mask and reservoir 304.

FIGS. 8A–8D depict side views of various stages of a process for forminga mold that can be used for forming a CC mask.

FIGS. 9A–9F depict side views of various stages of a CC mask formationprocess using the mold of FIGS. 8A–8D.

FIG. 10 depicts a side view of an alternate CC mask configuration thatincludes a porous support.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

FIGS. 1A–1G, 2A–2F, and 3A–3C illustrate various aspects ofelectrochemical fabrication that are known. Other electrochemicalfabrication techniques are set forth in the '630 patent referencedabove, in the various previously incorporated publications, in patentapplications incorporated herein by reference, still others may bederived from combinations of various approaches described in thesepublications, patents, and applications, or are otherwise known orascertainable by those of skill in the art. All of these techniques maybe combined with those of the present invention to yield enhancedembodiments.

Various embodiments of the invention present techniques for formingstructures (e.g. HARMS-type structures) via an electrochemical extrusion(ELEX™) process. Some preferred embodiments perform the extrusionprocess via depositions through an anodeless conformable contact maskthat is initially pressed against a substrate and is then progressivelypulled away from the substrate as the deposition thickens. The patternof deposition may vary over the course of deposition by includingrelative motion between the mask and the substrate that includestranslational or rotational components. More complex structures may beformed by combining the extrusion process with the selective deposition,blanket deposition, planarization, etching, and multi-layer operationsof the electrochemical fabrication processes set forth in the U.S. Pat.No. 6,027,630. In other embodiments, there may be no need for an initialface-to-face contact between the mask and the substrate particularly ifthe extrusion is to be added to an existing deposition where the contactcan begin with a mating of side walls. In still other embodiments themask may be placed in proximity to the substrate and an initialdeposition can be used to seal the mask and he substrate such that theinitial gap is at least partially filled with a deposition material.

In a first preferred embodiment, the mask is initially pressed againstthe substrate so that the face of its conformable material (e.g.elastomeric surface) conforms to the substrate as in CC mask platingillustrated in FIGS. 1A–1G. This contact positioning of the conformablecontract mask prevents any deposition of material in contacted regions.An expandable bellows chamber is provided that surrounds the substrateand prevents the deposition bath from contacting the sides or rear ofthe substrate as well as the sides of later deposits, and thus preventsdeposition in those regions. When the deposit has begun to grow inthickness, the substrate (or mask) is withdrawn at a controlled ratethat on average closely matches the deposition rate, such that theprogressing “working surface” (i.e. the surface at which the depositionis occurring) remains relatively fixed with respect to the mask. Duringthe movement, when the face of the mask no longer contacts thesubstrate, the sidewalls of the mask remain in intimate contact with thedeposit, thus forming a seal which prevents deposition other than in theopen areas of the mask. Eventually, a high aspect ratio structure, or atleast a structure having a height in excess of that normally allowed bya mask of given dimensions, may be generated which is easily separatedfrom the mask which can then be reused.

A first preferred embodiment is illustrated in FIGS. 5 A–5F. Thisembodiment uses a relatively thin mask (i.e. much thinner than the masksused in LIGA) that is independent of the substrate, and which is movedrelative to the substrate during deposition to extrude a structure.

FIGS. 5A–5F illustrate side views of various stages in the process ofthis embodiment along with the various components that are used in theembodiment. FIG. 5A illustrates a mask 102 that includes a supportportion 104 (e.g. a rigid or dimensionally stable structure) and aconformable portion 106, an electrode 108 that may function as an anode,a substrate 110, and a bellows 120 and bellows chamber 112 that arelocated within a deposition tank 114 that can hold an electrolyte 116(shown in FIG. 5B). The open side of the bellows 120 connects to andseals with a perimeter region of the mask 102. This sealing makes theopenings through the mask the only paths between the inside and outsideof the bellows. Next, as shown in FIG. 5B, the substrate 110 and themask 102 are pressed against each other and the tank 114 is filled withelectrolyte 116 in such a manner that the electrolyte does not becomelocated in the region 112 between the substrate and the bellows. Asshown in FIG. 5C a potential is applied between the anode 108 and thesubstrate 110 (which acts as a cathode) via power source 122 and wires124 and 126. The potential is supplied with a polarity and current thatallows a deposition 138 to begin forming on the substrate at anappropriate rate. The primary source of the deposition material ispreferably the anode 108 with potentially some deposition material beingsupplied directly by the electrolyte.

After the deposition thickens to a desired height, the substrate and themask begin to separate at a desired rate. The average rate of separationis preferably approximately equal to the average rate of deposition suchthat a deposition zone and a location on the mask surface stay in thesame approximate position throughout the deposition operation with theexception of the initial portion of the deposition that occurs beforemovement begins. During separation, the sidewalls 132 of the mask sealwith the sidewalls 134 of the growing deposit 138 such that theelectrolyte does not enter the bellows chamber 112. In one embodimentthe deposition rate and the movement occur in such a manner that theposition of the deposition stays at a position 140 relative to the facesurface 136 of the mask resulting in a separation of “L”. In otherembodiments though the average deposition rate and the separation rateare approximately equal, actual separation may occur in discrete anddiscontinuous steps while the deposition may occur in a continuousmanner, or in a discontinuous manner. Deposition and movement may occurin an alternating manner at different times. In some embodiments theworking surface may extend into the support region of the mask.

FIG. 5D depicts the state of deposition after the deposit thickness hasgrown to several times the thickness of the original mask and even moretimes the thickness of the conformable material portion 106 of the mask.FIG. 5E depicts the state of the process after the deposit 138 has grownto become the completed structure 142 has been completed to form thecompleted structure 142. FIG. 5F depicts the combined substrate 110 andstructure 142 after being removed from the apparatus of FIGS. 5A–5E.

FIG. 6 illustrates a side view of a structure 242 formed byelectrochemical extrusion of material onto substrate 210 via mask 202.During the formation of the structure 242 not only was there aperpendicular separation of the planes of the mask 202 and substrate 210surfaces but there was also motion that had a component parallel to theplanes of the mask and substrate surfaces. The parallel component ofmotion may include translational motion or may include rotational motionaround an axis that has a component that is perpendicular to a plane ofthe mask surface (i.e. the face of the conformable material) or of acontact face of the substrate surface.

FIGS. 7A–7C illustrate another preferred embodiment where the bellows ofthe first embodiment is removed in favor of other structural componentsthat inhibit deposition of material onto the sidewalls of the structureand onto the substrate (other than where initial openings in the maskexpose selected portions of the substrate to electrolyte).

FIG. 7A depicts a base structure 300 on which an electrolyte reservoir304 sits. A mask 302 sits on a gasket 308 located on a lower lip 306 atthe bottom of the electrolyte reservoir 304. Of course, as opposed tojust sitting on one another, in some embodiments the mask may beattached to the reservoir in any appropriate manner and similarly thereservoir may be attached to the base. On lip 306 and gasket 308, asupport portion 312 of mask 302 sits while a conformable portion 322 ofthe mask is located on a lower surface of the support portion 312. Oneor more openings for the desired deposition pattern (in this examplethree are depicted) extend through both the conformable material and thesupport portion of the mask. A substrate 324 on which deposition is tooccur is located below the mask on stage 332. Stage 332 is shown ashaving Z-movement capability 334 (i.e. movement capability in adirection substantially perpendicular to the plane of the substrate) butit is to be understood that for alignment purposes prior to beginningdeposition or for varying the deposition pattern in the a plane parallelto the plane of the substrate, stage 332 could offer X and/or Y motioncapability or rotational motion capability. FIG. 7A further shows thatthe apparatus includes an anode 334 that is located in electrolytereservoir 304, electrical connections 336, 338, and 340 that connect theanode 334, the substrate 324, and the stage 332 to controller 344.During operation the controller supplies appropriate power to the anodeand the substrate such that deposition onto the substrate occurs at adesirable rate and also supplies appropriate power to stage 332 suchthat the motion of the substrate 324 relative to the mask 302 isappropriately controlled.

As shown in FIG. 7B the conformable portion 322 of the mask 302 contactsthe substrate 324, the electrolyte reservoir 304 is filled withelectrolyte 342 such that anode 334 and substrate 324 are connected by aconductive path. Deposition begins formation of structure 352 prior toinitiating any movement of the substrate 324. In FIG. 7C, a furtherstage of the process is shown where a deposition of significant heighthas been formed.

In some alternative embodiments the process may not begin with aface-to-face mating of the substrate and the mask (where the faces areconsidered to be the surfaces of the mask and the substrate that aresubstantially perpendicular to a direction of the height of thedeposition). Instead the process may begin with a mating between thesidewalls of the mask and sidewalls of a protrusion that extends fromthe face of the substrate. Such an alternative process may be consideredan add-on process, as the depositions that occur simply add to anexisting structure. The initial protrusion may originate in many ways.For example, it may be from a molding operation, a previous extrusionoperation, or a non-extrusion based conformable contact mask platingoperation.

It is believed that these alternatives can be understood with referenceto FIG. 5E, 6, or 7C where the state of deposition in each may beconsidered a protrusion that extends from the substrate and onto whichone or more further depositions will occur. As such these figures may beconsidered to be the starting point of the process. These startingpoints are achieved by mating the protrusion to the mask either in thepresence of an electrolyte or subsequently surrounding the matedcombination with electrolyte. After mating and electrolyte immersion,follow-on deposition occurs.

The follow-on deposition is preferably accompanied by relative movementbetween the mask and the substrate. However, in some embodiments thefollow-on deposition may not be accompanied by such movement as the actof performing the deposition on an existing protrusion may be consideredas a type of extrusion. In some embodiments, depositions may occurmultiple times between mating and unmating operations where unmating andmating operations occur between relative movements of the mask and thesubstrate.

The controller 344 may take various forms. For example it may be acomputer programmed to control deposition time, current level for theelectrodeposition operations, start time for initiating relativemovement between the substrate and the mask, or the rate of suchmovement or the amount and timing of discrete movements, and the like.In less automated embodiments the controller may be two or more discretedevices and/or independent devices. For example, it may include aseparate power supply for the deposition operation and a separate powersupply and/or controller for the stage. The deposition power supply mayinclude an adjustment for setting current to a desired value (e.g. basedon a desired current density). The movement of the stage may becontrolled to begin after a predetermined deposition time, after apredetermined amount of charge as flowed or been transferred through thedeposition system, or after a determined or estimated deposition heighthas been achieved. In some tests performed, it was found that adeposition thickness of about 20 microns before allowing the extrusionmotion to begin resulted in reasonable sealing between the mask and thedeposit during movement (i.e. no extraneous deposits or at least noexcessive extraneous deposits were observed). Tests with a 10 micronthick deposition prior to initiating extrusion motion producedunsatisfactory results in those specific experiments. It is possiblethat in a given situation, thinner depositions prior to beginningextrusion motion could yield satisfactory results. It is within thelevel of skill in the art to determine a required minimum or at least aworkable deposition thickness in a given situation.

Deposition may be terminated after a predetermined deposition time (atime estimated to produce the desired deposition height or a minimumdeposition height to which the total deposition can be planed), after apredetermined amount of charge has flowed or been transferred throughthe deposition system, or after a determined or estimated depositionheight has been achieved. In some alternative embodiments, depositionheight may be periodically checked to ensure that movement anddeposition are progressing as anticipated, corrective action may betaken as needed, and/or build parameters may be updated based on devisedperformance data. In some embodiments, the current may be set based on adesired current density and a known or estimated surface area for thedeposition.

In some alternative embodiments, the movement between the mask and thesubstrate will be controlled in a manner that inhibits the depositionmaterial from reaching a height within the mask that allows thedeposited material to contact the support material. In other embodimentsthe deposition material will be allowed to contact the sidewalls of thesupport material

The movement of stage 332 may be manually controlled, semi-automaticallycontrolled, or automatically controlled (e.g. by a programmable device).

In some alternative embodiments, sealing between the mask and thereservoir may occur via the conformable material that forms part of themask. For example, the conformable material may have an outer diameterthat mates with the opening through the bottom of the reservoir 304(e.g. the inside dimension of lip 306) or it may extend completelyacross the support structure such that an outer ring of conformablematerial rests on the lip of the reservoir thereby potentially obviatingthe need for the gasket 308. This final alternative is shown in FIG. 7D.

In the most preferred embodiments the anode includes an erodablematerial that supplies the deposition material but in other embodimentsthe deposition material may be provided by other means (e.g. solely bythe solution) in which case the anode may not need to be erodable.

In the most preferred embodiments the mask is of the anodeless typewhile in other embodiments the anode may form part of the mask. In someanodeless type embodiments, the openings through the support materialmay be identical in size and configuration to the opening holes throughthe support portion while in other embodiments the opening sizes in theconformable material may be larger or smaller than the openings throughthe support material.

In still other embodiments, the support material may include a porousmaterial and openings through the support portion may be paths throughthe pores. An example of a mask 500 with a porous support is shown inFIG. 10. A conformable portion 504 (e.g. PDMS) of the mask 500 ispatterned and attached to a relatively thin solid support structure 502(e.g. a thin silicon wafer) that is in turn bonded to a porous structure506 (e.g. a glass frit). In the most preferred embodiments each of thesethree components would be dielectrics but in other embodiments the solidsupport and the porous structure can be conductive. It is believed thata p-type silicon material may be particularly advantageous as the solidsupport structure as it is believed to resist acceptance of deposits ofmaterial if the deposition height and relative motion of the mask andsubstrate allow the deposit to contact the solid support 502.

In some preferred embodiments the substrate material will be the same asthe deposition material while in other embodiments the materials may bedifferent. For example, the deposition material may be copper, nickel,gold, silver, an alloy, or the like, while the substrate material may beany of these materials or some other material and even a material thatisn't readily depositable. As a further example, the substrate may becomposed of pure nickel (99.98%) while the deposition material may comefrom an electrode (i.e. anode) of pure OFHC copper (99.95%). In someembodiments where copper is the deposition material, the electrolyte maybe a copper plating bath, such as a copper sulfate acid bath (e.g.Techni Copper U or Techni Copper FB from Technic Inc. of Cranston, R.I.)or a copper pyrophosphate bath (e.g. Unichrome from Atotech USA Inc. ofSomerset, N.J.).

The embodiment of FIG. 5 illustrated a sideways extrusion of thematerial while the embodiment of FIGS. 7A–7D illustrated a verticalextrusion of material where newly deposited material is added on top ofpreviously deposited material. In still other embodiments the mask andsubstrate may take on other orientations, for example the substrate maybe located above the mask. If the substrate is located above the maskany bubbles resulting from the deposition process may tend to get stuckwithin the mask against the substrate or previously deposited materialand a method to remove such bubbles may be desirable (e.g. flowing ofelectrolyte, agitation of electrolyte, periodic separation with orwithout associated agitation or flow, and the like).

In some embodiments, the structures may take on more complex forms. Forexample, the deposition material may be changed so that a portion of theextruded structure is formed from one material while another extrudedportion is formed from a different material. A first portion of theextruded structure may be formed with one mask pattern while anotherextruded portion may be formed with a different mask pattern. In stillother embodiments one or more breaks in deposition may occur, followedby one or more planarization operations. In other embodiments one ormore extrusion operations may be performed in combination with one ormore non-extrusion type deposition operations (e.g. depositionoperations that do not include relative movement between a mask and thesubstrate).

In some embodiments, a second material may be deposited eitherselectively or by blanket deposition. In some embodiments, single ormultiple materials may be planarized (e.g. by lapping, grinding,chemical mechanical polishing, and the like) as a basis for furtherdeposition operations either of the extrusion type or of thenon-extrusion type. In some embodiments multiple deposition operationsmay not occur in a repeated registration with each other but may occurin a desired shifted or rotated registration with respect to each other.In some multiple material embodiments, the material deposited byextrusion may be a sacrificial material while in other embodiments itmay be a structural material. In some embodiments selective and/ornon-selective depositions may be performed by electroplating,electrophoretic deposition, CVD, PVD, and/or any other technique capableof locating a material in a desired pattern on a substrate.

In some embodiments, for example to allow clearing of bubbles or toallow refreshing of electrolyte, the deposition current may be shut offone or more times, the mask and deposition may be separated, the maskand the deposition realigned and contacted, and then the currentreactivated. In some embodiments this shutting off, separating,re-contacting, and re-depositing may be accompanied by an intermediateplanarization operation (e.g. lapping) so as to allow reestablishment ofplanarity of the deposit prior to continuing with further deposition. Instill other embodiments, fresh electrolyte may be made to flow betweenthe anode and the back side (i.e. the support side) of the mask and/orsome agitation of the electrolyte may occur to help ensure maintenanceof electrolyte properties. In embodiments where electrolyte isrefreshed, replenished, or agitated, control of any pump or agitationactuator may occur via the same controller that handles deposition andseparation.

In some embodiments, the mask may only include the conformable portionof the mask. The conformable portion of the mask preferably hassufficient conformability to allow easy separation of the mask and thedeposit and to inhibit excessive amounts of electrolyte leakage betweenboth the mask and the substrate and the mask and the deposit. In someembodiments, it may be found that sufficient conformability for suchpurposes is achieved without resorting to the need for a more rigidsupport structure.

The conformable contact masks of various embodiments may be formed inmany different ways. The conformable material for some masks may be anelastomeric material, such as a rubber material, a urethane, or thelike. A rubber material may be a silicone rubber, such aspolydimethylsiloxane (PDMS). The supporting substrate or support may bea metal, silicon wafer, a relatively hard plastic or the like.

Some masks may be formed in a three step process that includes: (1)Design and fabrication of a photomask, (2) fabrication of a mold, and(3) fabrication of the mask. As some masks have feature sizes on theorder of tens to hundreds of microns, the molds that may be used inpatterning them may be considered micromolds.

Micromold fabrication may employ photolithography of a photoresist (suchas is used in IC fabrication) to realize features on the microscale. Onesuch photoresist is SU-8 (from Microchem Inc. of Newton, Mass.). SU-8 isa negative photoresist. It has good mechanical properties, can beadhered to silicon, and can be coated (e.g. from 1 μm to more than 500μm) in a single operation to a desired thickness (e.g. 25 μm to 100 μm).Silicon wafers offer excellent flatness and smoothness which can betransferred to the contact surface of a conformable material that ispatterned by an SU-8/silicon micromold.

A process that can be used to fabricate an SU-8/silicon micromold isillustrated in FIGS. 8A–8D. FIG. 8A depicts a side view of a siliconwafer 402. FIG. 8B shows that a coating of photoresist 406 (e.g. SU-8)of desired thickness is applied to the surface of the wafer 402. FIG. 8Cillustrates the use of a photomask 412 in combination with a source (notshown) of UV radiation 416 can be used to selective expose 418 thecoating of photoresist 406. FIG. 8D depicts mold 424 that results fromthe development of the photoresist 406 that was patterned via of theexposure of FIG. 8C. In FIG. 8D a region of photoresist 426 (the portionof the resist that was exposed) remains on the silicon wafer 402.

A process for using a mold, such as that shown in FIG. 8D to form asilicon/silicone mask, is depicted in FIGS. 9A–9F. The process includesthe following operations or steps: (0) Start with a mold 424 as shown inFIG. 9A which includes base 402 and patterned photoresist 426, (1) Pourliquid PDMS 450 over photoresist pattern 426 of the mold 424 as shown inFIG. 9B, (2) degas the PDMS to remove air bubbles, (3) place a Si wafer452 onto the PDMS 450, pressing it down as indicated by arrows 454 asshown in FIG. 9C and holding it in position (e.g. with a moldingfixture), and putting the fixture in an oven at an elevated temperature(e.g. 65° C.) for a period of time sufficient to cure the PDMS (e.g. forabout 6 hours) to form a pattern 456 of cured PDMS, (4) de-mold thepartially formed mask 458 from the mold as shown in FIG. 9D. Thepartially formed mask may include a silicone residue 464 on the silicon452 that is exposed in the opening 462 in the silicone, (5) use anetching operation (e.g. RIE) to remove any silicone residue from thesilicon surface in the opening to yield a partially formed mask 458 withan opening that is free of silicone as shown in FIG. 9E, and (6) usedeep reactive ion etching (DRIE) to etch through the silicon wafer toyield a completed anodeless mask 472 as shown in FIG. 9F. Prior toperforming the coating operation of step (2) above, the surface of thephotoresist and silicon wafer of the mold may be treated with a releaseagent that may aid in the de-molding process of step (4). Experimentshave produced masks by this process where the resulting conformablematerial thickness is about 25 μm with a silicon thickness of about 300μm.

In some embodiments, the silicon thickness could be reduced so as toreduce the required time to etch through it. For example, SOI waferscould be used. In other embodiments, a sacrificial film may be used toprotect the conformable material (e.g. PDMS) during DRIE operations.

The patent applications in the following table are hereby incorporatedby reference herein as if set forth in full. The gist of each patentapplication is included in the table to aid the reader in findingspecific types of teachings. It is not intended that the incorporationof subject matter be limited to those topics specifically indicated, butinstead the incorporation is to include all subject matter found inthese applications. The teachings in these incorporated applications canbe combined with the teachings of the instant application in many ways.For example, the various apparatus configurations disclosed in thesereferenced applications may be used in conjunction with the novelfeatures of the instant invention to provide various alternativeapparatus that include the functionality disclosed herein:

U.S. Application No. Title Filing Date Brief Description U.S. App. No.Method for Electrochemical Fabrication 09/488,142 This application is adivisional of the application Jan. 20, 2000 that led to the above noted‘630 patent. This application describes the basics of conformablecontact mask plating and electrochemical fabrica- tion including variousalternative methods and apparatus for practicing EFAB as well as variousmethods and apparatus for constructing conformable contact masks U.S.App. No. Microcombustor and Combustion-Based 09/755,985 ThermoelectricMicrogenerator Jan. 5, 2001 Describes a generally toroidal counterflowheat exchanger and electric current microgenerator that can be formedusing electrochemical fabrication. U.S. App. No. SelectiveElectrochemical Deposition Methods 60/379,136 Having Enhanced UniformDeposition May 7, 2002 Capabilities Describes conformable contact maskprocesses for forming selective depositions of copper using a copperpyrophosphate plating solution that allows simultaneous deposition to atleast one large area (greater than about 1.44 mm²) and at least onesmall area (smaller than about 0.05 mm²) wherein the thickness ofdeposition to the smaller area is no less than one-half the depositionthickness to the large area when the deposition to the large area is noless than about 10 μm in thickness and where the copper pyrophosphatesolution contains at least 30 g/L of copper. The conformable contactmask process is particularly focused on an electrochemical fabricationprocess for pro- ducing three-dimensional structures from a plurality ofadhered layers. U.S. App. No. Selective Electrodeposition UsingConformable 60/379,131 Contact Masks Having Enhanced Longevity May 7,2002 Describes conformable contact masks that include a supportstructure and a patterned elastomeric material and treating the supportstructure with a corrosion inhibitor prior to combining the support andthe patterned elastomeric material to improve the useful life of themask. Also describes operating the plating bath at a low temperature soas to extend the life of the mask. U.S. App. No. Methods and Apparatusfor Monitoring 60/379,132 Deposition Quality During Conformable ContactMay 7, 2002 Mask Plating Operations Describes an electrochemicalfabrication process and apparatus that includes monitoring of at leastone electrical parameter (e.g. voltage) during selective depositionusing conformable contact masks where the monitored parameter is used tohelp determine the quality of the deposition that was made. If themonitored parameter indicates that a problem occurred with thedeposition, various remedial operations are undertaken to allowsuccessful formation of the structure to be completed. U.S. App. No.“Innovative Low-Cost Manufacturing Technology 60/329,654 for High AspectRatio Microelectromechanical Oct. 15, 2001 Systems (MEMS)” This is theparent application for the present application and describes aconformable contact masking technique where the depth of deposition isenhanced by pulling the mask away from the substrate as deposition isoccurring in such away that the seal between the conformable portion ofthe mask and the substrate shifts from the face of the conformalmaterial and the opposing face of the substrate to the inside edges ofthe conformable material and the deposited material. U.S. App. No.Conformable Contact Masking Methods and 60/379,129 Apparatus UtilizingIn Situ Cathodic Activation May 7, 2002 of a Substrate Describes anelectrochemical fabrication process benefiting from an in situ cathodicactivation of nickel where prior to nickel deposition, the sub- strateis exposed to the desired nickel plating solution and a current lessthan that capable of causing deposition is applied through the platingsolution to the substrate (i.e. cathode) to cause activation of thesubstrate, after which, without removing the substrate from the platingbath, the current is increased to a level which causes deposition tooccur. U.S. App. No. Electrochemical Fabrication Methods With 60/379,134Enhanced Post Deposition Processing May 7, 2002 Describes anelectrochemical fabrication process for producing three-dimensionalstructures from a plurality of adhered layers where each layer in-cludes at least one structural material (e.g. nickel) and at least onesacrificial material (i.e. copper) that will be etched away from thestructural material after the formation of all layers have beencompleted. A copper etchant containing chlorite (e.g. Enthone C-38) iscombined with a corrosion inhibitor (e.g. sodium nitrate) to preventpitting of the structural material during removal of the sacrificialmaterial. U.S. App. No. Electrochemical Fabrication Method and60/364,261 Apparatus for Producing Three-Dimensional Mar. 13, 2002Structures Having Improved Surface Finish Describes an electrochemicalfabrication (e.g. EFAB ™) process and apparatus provided that removematerial deposited on at least one layer using a first removal processthat includes one or more operations having one or more parameters, andremove material deposited on at least one different layer using a secondremoval process that includes one or more operations having one or moreparameters, wherein the first removal process differs from the secondremoval process by inclusion of at least one different operation or atleast one different parameter. U.S. App. No. Method of and Apparatus forForming Three- 60/379,133 Dimensional Structures Integral With May 7,2002 Semiconductor Based Circuitry Describes an electrochemicalfabrication (e.g. by EFAB ™) process and apparatus that can formthree-dimensional multi-layer structures using semiconductor basedcircuitry as a substrate. Electrically functional portions of thestructure are formed from structural material (e.g. nickel) that adheresto contact pads of the circuit. Aluminum contact pads and siliconstructures are protected from copper diffusion damage by application ofappropriate barrier layers. In some embodiments, nickel is applied tothe aluminum contact pad via solder bump formation techniques usingelectroless nickel plating. U.S. App. No. Selective ElectrochemicalDeposition Methods 60/379,176 Using Pyrophosphate Copper Plating BathsMay 7, 2002 Containing Citrate Salts Describes an electrochemicalfabrication (e.g. by EFAB ™) process and apparatus that can form three-dimensional multi-layer structures using pyrophosphate copper platingsolutions that contain a citrate salt. In preferred embodiments thecitrate salts are provided in concentrations that yield improved anodedissolution, reduced formation of pinholes on the surface of deposits,reduced likelihood of shorting between anode and cathode duringdeposition processes, and reduced plating voltage throughout the periodof deposition. A preferred citrate salt is ammonium citrate inconcentrations ranging from somewhat more that about 10 g/L for 10mA/cm² current density to as high as 200 g/L or more for a currentdensity as high as 40 mA/cm². U.S. App. No. Methods of and Apparatus forMolding Structures 60/379,135 Using Sacrificial Metal Patterns May 7,2002 Describes molded structures, methods of and apparatus for producingthe molded structures. At least a portion of the surface features forthe molds are formed from multilayer electrochemi- cally fabricatedstructures (e.g. fabricated by the EFAB ™ formation process), andtypically contain features having resolutions within the 1 to 100 μmrange. The layered structure is com- bined with other mold components,as necessary, and a molding material is injected into the mold andhardened. The layered structure is removed (e.g. by etching) along withany other mold components to yield the molded article. In someembodiments portions of the layered structure remain in the moldedarticle and in other embodiments an additional molding material is addedafter a partial or complete removal of the layered structure. U.S. App.No. Electrochemically Fabricated Structures Having 60/379,177 DielectricBases and Methods of and Apparatus May 7, 2002 for Producing SuchStructures Describes multilayer structures that are electrochemicallyfabricated (e.g. by EFAB ™) on a temporary conductive substrate and arethereafter are bonded to a permanent dielectric substrate and removedfrom the temporary substrate. The structures are formed from top layerto bottom layer, such that the bottom layer of the structure becomesadhered to the permanent substrate. The permanent substrate may be asolid sheet that is bonded (e.g. by an adhesive) to the layeredstructure or the permanent substrate may be a flowable material that issolidified adjacent to or partially surrounding a portion of thestructure with bonding occurs during solidification. The multilayerstructure may be released from a sacrificial material prior to attach-ing the permanent substrate or more preferably it may be released afterattachment. U.S. App. No. Electrochemically Fabricated HermeticallySealed 60/379,182 Microstructures and Methods of and Apparatus May 7,2002 for Producing Such Structures Describes multilayer structures thatare electrochemically fabricated (e.g. by EFAB ™) from at least onestructural material (e.g. nickel), at least one sacrificial material(e.g. copper), and at least one sealing material (e.g. solder). Thelayered structure is made to have a desired con- figuration which is atleast partially and immedi- ately surrounded by sacrificial materialwhich is in turn surrounded almost entirely by structural material. Thesurrounding structural material in- cludes openings in the surfacethrough which etchant can attack and remove trapped sacrificial materialfound within. Sealing material is located near the openings. Afterremoval of the sacrificial material, the box is evacuated or filled witha desired gas or liquid. Thereafter, the sealing material is made toflow, seal the openings, and resolidify. U.S. App. No. Multistep ReleaseMethod for Electrochemically 60/379,184 Fabricated Structures May 7,2002 Describes multilayer structures that are electrochemicallyfabricated (e.g. by EFAB ™) from at least one structural material (e.g.nickel), that is configured to define a desired structure and which maybe attached to a support structure, and at least a first sacrificialmaterial (e.g. copper) that surrounds the desired structure, and atleast one more material which surrounds the first sacrificial materialand which will function as a second sacrificial material. The secondsacrificial material is removed by an etchant and/or process that doesnot attack the first sacrificial material. Intermediate post processingactivities may occur, and then the first sacrificial material is removedby an etchant or process that does not attack the at least onestructural material to complete the release of the desired structure.U.S. App. No. Miniature RF and Microwave Components and 60/392531Methods for Fabricating Such Components Jun. 27, 2002 RF and microwaveradiation directing or control- ling components describes that aremonolithic, that are formed from a plurality of electro- depositionoperations, that are formed from a plurality of deposited layers ofmaterial, that in- clude inductive and capacitive stubs or spokes thatshort a central conductor of a coaxial com- ponent to the an outerconductor of the com- ponent, that include non-radiation-entry and non-radiation-exit channels that are useful in separating sacrificialmaterials from structural materials and that are useful, and/or thatinclude surface ripples on the inside surfaces of some radiation flowpassages. Preferred formation processes use electrochemical fabricationtechniques (e.g. including selective depositions, bulk depositions,etching operations and planarization operations) and post-depositionprocesses (e.g. selective etching operations and/or back fillingoperations). U.S. App. No. Multi-cell Masks and Method and Apparatus for60/415,371 Using Such Masks To Form Three-Dimensional Oct. 1, 2002Structures Describes multilayer structures that are electrochemicallyfabricated via depositions of one or more materials in a plurality ofoverlaying and adhered layers. Selectivity of deposition is obtained viaa multi-cell controllable mask. Alternatively, net selective depositionis obtained via a blanket deposition and a selective removal of materialvia a multi-cell mask. Individual cells of the mask may containelectrodes comprising depositable material or electrodes capable ofreceiving etched material from a substrate. Alternatively, individualcells may include passages that allow or inhibit ion flow between asubstrate and an external electrode and that in- clude electrodes orother control elements that can be used to selectively allow or inhibition flow and thus inhibit significant deposition or etching. U.S. App.No. Monolithic Structures Including Alignment and/or 60/415,374Retention Fixtures for Accepting Components Oct. 1, 2002 Describespermanent or temporary alignment and/or retention structures forreceiving multiple components. The structures are preferably formedmonolithically via a plurality of deposition operations (e.g.electrodeposition operations). The structures typically include two ormore positioning fixtures that control or aid in the positioning ofcomponents relative to one another, such features may include (1)positioning guides or stops that fix or at least partially limit thepositioning of components in one or more orientations or directions, (2)retention elements that hold positioned components in desiredorientations or locations, and (3) positioning and/or retention elementsthat receive and hold adjustment modules into which components can befixed and which in turn can be used for fine adjustments of positionand/or orientation of the components.

Various other embodiments of the present invention exist. Some of theseembodiments may be based on a combination of the teachings herein withvarious teachings incorporated herein by reference. Some embodiments maynot use any blanket deposition process and/or they may not use aplanarization process. Some embodiments may involve the selectivedeposition of a plurality of different materials on a single layer or ondifferent layers. Some embodiments may use blanket depositions processesthat are not electrodeposition processes. Some embodiments may useselective deposition processes on some layers that are not conformablecontact masking processes and are not even electrodeposition processes.Some embodiments may use nickel as a structural material while otherembodiments may use different materials such as gold, silver, or anyother electrodepositable materials that can be separated from copperand/or some other sacrificial material. Some embodiments may use copperas the structural material with or without a sacrificial material. Someembodiments may remove a sacrificial material while other embodimentsmay not. Some embodiments may use multiple conformable contact maskswith different patterns so as to deposit different selective patterns ofmaterial on different layers and/or on different portions of a singlelayer.

In view of the teachings herein, many further embodiments, alternativesin design and uses of the instant invention will be apparent to those ofskill in the art. As such, it is not intended that the invention belimited to the particular illustrative embodiments, alternatives, anduses described above but instead that it be solely limited by the claimspresented hereafter.

1. A method of producing a three-dimensional structure, comprising:providing an anode; providing a substrate that functions as a cathode;providing an electrolyte between the anode and the cathode; providing acurrent source controllably connected to the anode and cathode;providing a mask that comprises an at least partially conformabledielectric material, the mask having at least one opening extendingthrough the at least partially conformable dielectric material whereinthe opening is defined by mask sidewalls and wherein the opening definesa mask pattern, the at least partially conformable dielectric materialalso having a face surface which forms a face surface of the mask;pressing the face surface of the mask against the substrate; after thepressing, activating the current source to cause depositing of adeposition material onto the substrate in a deposition pattern at leastpartially dictated by the pattern of the mask, wherein the depositeddeposition material comprises deposition sidewalls; and after saidactivating, relatively moving the face surface of the mask away from thesubstrate by a distance that is less than a distance that would causeseparation of the mask sidewalls from the deposition sidewalls, andcontinuing application of current so as to allow a height of thedeposited deposition material to increase.
 2. The method of claim 1wherein the moving continues during continued depositing of thedeposition material at a rate that maintains contact between thedeposition sidewalls and the sidewalls of the mask and for a time periodthat allows a full height of the deposited deposition material to bereached.
 3. The method of claim 1 wherein the substrate comprises amaterial that is different from the deposition material.
 4. The methodof claim 1 wherein the current is set as a function of known orestimated surface area of the at least one opening in the mask.
 5. Themethod of claim 1 wherein the mask further comprises a support materialwith the at least one opening extending through each of the at leastpartially conformable material and the support material and with the atleast partially conformable material and the support material havingsidewalls.
 6. The method of claim 5 wherein during at least a portion ofthe depositing, the deposition sidewalls contact sidewalls of thesupport material.
 7. The method of claim 5 wherein during thedepositing, the deposition sidewalls do not come into contact withsidewalls of the support material.
 8. The method of claim 5 wherein thesupport material comprises a porous material.
 9. The method of claim 1wherein the mask is a first mask, the deposition material comprises afirst deposition material, and the deposition pattern comprises a firstpattern and wherein after depositing the first deposition material asecond mask is used in forming a second height of a second depositionmaterial in a second pattern adhered to and having a desiredregistration with the first pattern.
 10. The method of claim 9 whereinthe first pattern is different from the second pattern.
 11. The methodof claim 9 wherein the first pattern is substantially identical to thesecond pattern.
 12. The method of claim 9 wherein the first depositionmaterial comprises a material that is different from the seconddeposition material.
 13. The method of claim 9 wherein the seconddeposition material comprises a material that is different from thefirst deposition material.
 14. The method of claim 9 wherein the firstdeposition material is substantially identical to the second depositionmaterial.
 15. The method of claim 9 wherein the current is periodicallyshut off and the mask and the deposited deposition material areseparated and lapping is performed to reestablish planarity of thedeposited deposition material and then the mask and substrate arealigned, contact between the mask and the deposited deposition materialis achieved, and the current is reactivated.
 16. The method of claim 1wherein the depositing of the deposition material comprises depositing afirst deposition material followed by depositing a second depositionmaterial that adheres to the first deposition material.
 17. The methodof claim 1 wherein lapping is used to establish co-planarity of asurface of the substrate with a surface of the mask.
 18. The method ofclaim 1 wherein relative movement between the mask and the substratecomprises movement having a component that is parallel to a plane of theface surface of the mask.
 19. The method of claim 18 wherein themovement having a component that is parallel to a plane of the facesurface of the mask comprises a translational movement.
 20. The methodof claim 18 wherein the movement having a component that is parallel toa plane of the face surface of the mask comprises rotational movementaround an axis that has a component that is perpendicular to the planeof the face surface of the mask.
 21. The method of claim 1 wherein themask comprises the anode.
 22. The method of claim 1 wherein thedeposition material is a first material, and additionally comprising:deactivating the current source; separating the mask and the depositedfirst material; depositing a second material to at least a portion ofany regions that did not receive a deposit of the first material;planarizing the first and second materials such that a common surfacelevel is formed; and depositing a third material onto at least a portionof a defined by the common surface level wherein the third materialcomprises a material selected from the group consisting of (1) amaterial that is identical to the first material, (2) a material that isidentical to the second material, and (3) a material that is differentfrom both the first and second materials.
 23. The method of claim 1wherein the height of the deposited deposition material exceeds a heightof the at least partially conformable dielectric material.
 24. Themethod of claim 23 wherein the mask additionally comprises a supportmaterial and wherein the height of the deposited deposition materialexceeds a combined height of the at least partially conformabledielectric material and the support material.
 25. The method of claim 1wherein the structure comprises at least a portion of the depositeddeposition material.
 26. The method of claim 1 wherein at least a secondmaterial is deposited in a region proximate to the deposited depositionmaterial and a desired structure comprises at least the second materialand at least a majority of the deposited deposition material is asacrificial material that is removed prior to putting the structure touse.
 27. A method of producing a three-dimensional structure,comprising: providing an anode; providing a substrate that functions asa cathode; providing an electrolyte between the anode and the cathode;providing a current source controllably connected to the anode andcathode; providing a mask that comprises an at least partiallyconformable dielectric material, the mask having at least one openingextending through the at least partially conformable dielectric materialwherein the opening is defined by mask sidewalls and wherein the openingdefines a mask pattern, the at least partially conformable dielectricmaterial also having a face surface which forms a face surface of themask; pressing the face surface of the mask against the substrate; afterthe pressing, activating the current source to cause depositing of adeposition material onto the substrate in a deposition pattern at leastpartially dictated by the pattern of the mask, wherein the depositeddeposition material comprises deposition sidewalls; and after saidactivating, relatively moving the face surface of the mask away from thesubstrate during the depositing of the deposition material orperiodically between a plurality of successive depositing operations bya distance that is less than a distance that would cause separation ofthe mask sidewalls from the deposition sidewalls, and continuingapplication of current such that contact between the depositionsidewalls and the sidewalls of the mask is maintained and such that afull height of the deposited deposition material is reached.
 28. Amethod of producing a three-dimensional structure, comprising: providingan anode; providing a substrate that functions as a cathode; providingan electrolyte between the anode and the cathode; providing a currentsource controllably connected to the anode and cathode; providing a maskthat comprises an at least partially conformable dielectric material,the mask having at least one opening extending through the at leastpartially conformable dielectric material wherein the opening is definedby mask sidewalls and wherein the opening defines a mask pattern, the atleast partially conformable dielectric material also having a facesurface which forms a face surface of the mask; pressing the facesurface of the mask against the substrate; after the pressing,activating the current source to cause depositing of a depositionmaterial onto the substrate in a deposition pattern at least partiallydictated by the pattern of the mask, wherein the deposited depositionmaterial comprises deposition sidewalls; and after said activating andafter allowing a result selected from the group of (1) depositing tooccur for a selected time, (2) the deposited deposition material toreach a selected minimum height, or (3) a desired charge transfer tooccur, relatively moving the face surface of the mask away from thesubstrate by a distance that is less than a distance that would causeseparation of the mask sidewalls from the deposition sidewalls andcontinuing application of current.
 29. The method of claim 28 whereinthe moving occurs at a substantially continuous rate.
 30. The method ofclaim 5 wherein the moving is correlated to an estimated or known rateof deposition.
 31. The method of claim 28 wherein the moving occurs viadiscrete increments separated by one or more periods of waiting.
 32. Amethod of producing a three-dimensional structure, comprising: providingan anode; providing a substrate that functions as a cathode; providingan electrolyte between the anode and the cathode; providing a currentsource controllably connected to the anode and cathode; providing a maskthat comprises an at least partially conformable dielectric material,the mask having at least one opening extending through the at leastpartially conformable dielectric material wherein the opening is definedby mask sidewalls and wherein the opening defines a mask pattern, the atleast Partially conformable dielectric material also having a facesurface which forms a face surface of the mask; pressing the facesurface of the mask against the substrate; after the pressing,activating the current source to cause depositing of a depositionmaterial onto the substrate in a deposition pattern at least partiallydictated by the pattern of the mask, wherein the deposited depositionmaterial comprises deposition sidewalls; and after said activating,relatively moving the face surface of the mask away from the substrateby a distance that is less than a distance that would cause separationof the mask sidewalls from the deposition sidewalls, and continuingapplication of the current, wherein the anode and the mask are separatedfrom each other by the electrolyte.
 33. A method of producing athree-dimensional structure, comprising: providing an anode; providing asubstrate that functions as a cathode; providing an electrolyte betweenthe anode and the cathode; providing a current source controllablyconnected to the anode and cathode; providing a mask that comprises anat least partially conformable dielectric material, the mask having atleast one opening extending through the at least partially conformabledielectric material wherein the opening is defined by mask sidewalls andwherein the opening defines a mask pattern, the at least partiallyconformable dielectric material also having a face surface which forms aface surface of the mask; pressing the face surface of the mask againstthe substrate; after the pressing, activating the current source tocause depositing of a deposition material onto the substrate in adeposition pattern at least partially dictated by the pattern of themask, wherein the deposited deposition material comprises depositionsidewalls; and after said activating, relatively moving the face surfaceof the mask away from the substrate by a distance that is less than adistance that would cause separation of the mask sidewalls from thedeposition sidewalls, and continuing application of current, where afterthe current is shut off at least once and the mask and depositeddeposition material are then separated, the mask and the depositeddeposition material are aligned and contacted, and then the current isreactivated.
 34. A method of producing a three-dimensional structure,comprising: providing an anode; providing a substrate that functions asa cathode, where the substrate comprises a face surface and may comprisea protrusion having sidewalls that extends from the face surface;providing an electrolyte between the anode and the cathode; providing acurrent source controllably connected to the anode and cathode;providing a mask that comprises an at least partially conformabledielectric material, the mask having at least one opening extendingthrough the partially conformable dielectric material wherein theopening is defined by mask sidewalls and wherein the opening defines amask pattern, the at least partially conformable dielectric materialalso having a face surface which forms a face surface of the mask;mating the face surface of the mask against the face surface of thesubstrate, or mating the mask sidewalls to the sidewalls of theprotrusion; after the mating, activating the current source to causedepositing of a deposition material onto the substrate in a depositionpattern that is at least partially dictated by the pattern of the mask,wherein the deposited deposition material comprises depositionsidewalls; and after said activating, relatively moving the face surfaceof the mask away from the substrate by a distance that is less than adistance that would cause separation of the mask sidewalls from at leastone of the protrusion sidewalls or the deposition sidewalls, andcontinuing application of the current so as to allow a height of thedeposited deposition material to increase.